Thermal batteries are single discharge reserve batteries that provide very long shelf life, e.g., often greater than 25 years, minimal self-discharge, wide storage temperature range, fast activation under sudden power demand, and wide range of temperature operating conditions. This is provided with application of molten salt electrolyte, which is in solid form under normal conditions and provides practically negligible ionic conductivity. This minimizes degradation mechanisms and self-discharge, and maximizes shelf life at wide storage temperature range. Under power demand, an internal pyrotechnic charge is activated and generates sufficient heat to elevate the battery temperature over melting temperature of the molten salt electrolyte (typically above 350° C.). The battery thermal activation allows for fast ion mobility, increase in battery voltage, and utilization of the charge transfer reaction.
Previously, the most advanced common configurations of thermal batteries featured lithium-silicon alloy powder as anode material, FeS2 as cathode material, and an eutectic electrolyte such as LiCl—KCl or halide electrolyte mixture of LiCl—LiF—LiBr. These configurations operate at voltage less than 2 V and the capacity is limited, e.g., limited to 485 mAh/g for Li13Si4 alloy, and 335 mAh/g for FeS2. These configurations cannot meet the requirements of new applications that are demanding high power and energy density. Moreover, the manufacturing of batteries based on these materials is hazardous due to the use of very reactive components in the anode.
Despite advances in thermal battery research, there is still a scarcity of methods and compositions that allow for high performance thermal batteries with the enhanced discharge capacity, improved discharge power, increased cell voltage, and the energy required, for example, for current munitions and defense applications, while at the same time allow for less hazardous manufacturing. What is needed are compositions and anodes, cathodes and batteries comprising compositions that meet this need for improved function.